The purpose of this post is to clarify important issues about cardiac devices as they relate to deactivation. As I wrote yesterday, Paula Span of the New York Times covered this important issue last week [1] . Her coverage came about because of this Mayo Clinic paper published in JAMA Internal Medicine [2] , which showed most patients with cardiac devices approach end of life without proper preparation.

The first two questions to clarify are: What is a cardiac device, and what does it mean to deactivate it? When we say "cardiac device" we are referring to either an internal cardiac defibrillator (ICD) or a pacemaker. There are many important differences; I will discuss the ones pertaining to deactivation later.
In the real world, the overwhelming majority of requests for deactivation (my guess is 999/1000) are to turn off ICD shocks. Recall that an ICD serves two main functions: it senses then treats dangerously fast rhythms with either painless overdrive pacing or (not painless) high-voltage shocks; and comes with built-in pacing capability for slow heart rhythms. This differs from a pacemaker, which is used only to treat slow heart rates.

When a patient with an ICD approaches end of life, it is appropriate to deactivate shocks. This is because shocks are painful and often anxiety provoking. What's more, and this is too often forgotten, a shock for sudden cardiac arrest prevents the kind of death most people hope for—a painless, quick, and peaceful death. A good death.

The critical point here is that deactivating shocks on an ICD has no immediate effect for the patient. None. Consider that most terminal patients request to be DNR (do not resuscitate) or AND (allow natural death). All we are doing by deactivating shocks is complying with a patient's wishes. I like to explain to patients that not having shocks programmed on makes you like me—or anybody else without an ICD.

There is an immense difference between turning off ICD shocks and turning off a pacemaker. Cardiac pacing, unlike ICD shocks, does not burden the dying patient. Most patients cannot feel the difference between a paced heartbeat and a native heartbeat. In fact, many patients with pacemakers do not depend on their device. They have their own native heartbeat. There are, however, patients who depend on their pacemakers. These "pacemaker-dependent" patients have either no underlying native heartbeat or they have an inadequate rate. When a pacemaker is turned off in a dependent patient, death comes quickly—but not always immediately, sometimes over hours to days. (The heart is amazing that way. It's equipped with escape rhythms, and rarely does it just stop stone cold.)

I mention the issue of pacing because the Mayo Clinic researchers reported in their series that six pacemaker-dependent patients requested deactivation. This very unusual finding was unfortunate—in that it distracts us from the more common matter of ICD shock deactivation. I call it unfortunate and distracting for two reasons: one is that pacemaker-deactivation requests are rare. In my 18 years, I've never been asked to turn off a pacemaker in a dependent patient. Yesterday, a device rep with 30 years of experience told me he has never had that request either. My wife is a hospice physician. The issue has come up only twice for her, and both times she was able to convince the family that the pacemaker was not prolonging death.

The other reason this finding was distracting is that it adds ethical controversy that need not be there: whereas nothing happens when ICD shocks are deactivated, death comes soon after turning off pacing in a dependent patient. That confuses people. It makes both doctors and patients think pacemaker deactivation is euthanasia or physician-assisted suicide. It is neither. The Heart Rhythm Society (HRS) issued an expert consensus statement on the subject [3] .

Here is my reasoning:

• As human beings, patients are free and equal.
• They have a right of self-determination—a tenet consistent with all major religions.
• We also assume patients (or their surrogates) are making an informed decision.
• A pacemaker is a battery-driven form of life support. It belongs to the patient, not us. In this way, a pacemaker is like mechanical ventilation or renal dialysis. Although inside the body, the pacemaker is extra, unlike, say, a heart valve that has been endothelialized (grown into the body) and would take extraordinary measures to remove.
• No one would argue that a patient should be forced to have a pacemaker implanted in the first place. We don't tie patients down for surgery.
• In the same way, then, we mustn't force a patient to keep his pacemaker functioning against his or her wishes. And it doesn't require surgery to stop the pacemaker; it can be switched off easily using a programming device in the room (wirelessly). That fact bothers some of those who oppose the notion of pacing deactivation. I respectfully disagree. I see pacing as external, like a respirator or dialysis, which no one argues can be stopped if a patient no longer wants it.

The major issue with cardiac devices in terminally ill patients is ICD shocks. We should not let the rare case of pacemaker deactivation distract us from the issue of dealing with ICD shock deactivation.

ICDs are high-voltage delivery machines. They are no small hammer. The findings from Mayo Clinic, likely a best-case scenario, should serve as a wake-up call for patients and caregivers alike. For doctors, educating ICD patients about deactivation should be as important as explaining any other aspect of the device. For patients in the current medical climate, where death is too often treated as optional, being prepared for the inevitable has never been more important.

Not to be glib, but if I were facing that final curtain and lived in a jurisdiction where getting the shocking function turned off was difficult or impossible, I'd be instructing someone to bring me a super magnet and some tape! Perhaps I'll buy a ICD-purposed magnet someday when my health starts to decline too far.